Robert Ly | 12a1de0 | 2011-11-02 11:56:50 -0700 | [diff] [blame] | 1 | page.title=Wi-Fi Direct |
| 2 | |
| 3 | @jd:body |
| 4 | |
| 5 | <div id="qv-wrapper"> |
| 6 | <div id="qv"> |
| 7 | <h2>In this document</h2> |
| 8 | |
| 9 | <ol> |
| 10 | <li><a href="#api">API Overview</a></li> |
| 11 | <li><a href="#creating-br">Creating a Broadcast Receiver for Wi-Fi Direct Intents</a></li> |
| 12 | |
| 13 | <li> |
| 14 | <a href="#creating-app">Creating a Wi-Fi Direct Application</a> |
| 15 | |
| 16 | <ol> |
| 17 | <li><a href="#setup">Initial setup</a></li> |
| 18 | |
| 19 | <li><a href="#discovering">Discovering peers</a></li> |
| 20 | |
| 21 | <li><a href="#connecting">Connecting to peers</a></li> |
| 22 | |
| 23 | <li><a href="#transferring">Transferring data</a></li> |
| 24 | </ol> |
| 25 | </li> |
| 26 | </ol> |
| 27 | <h2>Related Samples</h2> |
| 28 | <ol> |
| 29 | <li><a href="{@docRoot}resources/samples/WiFiDirectDemo/index.html">Wi-Fi Direct Demo</a></li> |
| 30 | </ol> |
| 31 | </div> |
| 32 | </div> |
| 33 | |
| 34 | <p>Wi-Fi Direct allows Android 4.0 (API level 14) or later devices with the appropriate hardware |
| 35 | to connect directly to each other via Wi-Fi without an intermediate access point. |
| 36 | Using these APIs, you can discover and connect to other devices when each device supports Wi-Fi Direct, |
| 37 | then communicate over a speedy connection across distances much longer than a Bluetooth connection. |
| 38 | This is useful for applications that share data among users, such as a multiplayer game or |
| 39 | a photo sharing application.</p> |
| 40 | |
| 41 | <p>The Wi-Fi Direct APIs consist of the following main parts:</p> |
| 42 | |
| 43 | <ul> |
| 44 | <li>Methods that allow you to discover, request, and connect to peers are defined |
| 45 | in the {@link android.net.wifi.p2p.WifiP2pManager} class.</li> |
| 46 | |
| 47 | <li>Listeners that allow you to be notified of the success or failure of {@link |
| 48 | android.net.wifi.p2p.WifiP2pManager} method calls. When calling {@link |
| 49 | android.net.wifi.p2p.WifiP2pManager} methods, each method can receive a specific listener |
| 50 | passed in as a parameter.</li> |
| 51 | |
| 52 | <li>Intents that notify you of specific events detected by the Wi-Fi Direct framework, |
| 53 | such as a dropped connection or a newly discovered peer.</li> |
| 54 | </ul> |
| 55 | |
| 56 | <p>You often use these three main components of the APIs together. For example, you can |
| 57 | provide a {@link android.net.wifi.p2p.WifiP2pManager.ActionListener} to a call to {@link |
| 58 | android.net.wifi.p2p.WifiP2pManager#discoverPeers discoverPeers()}, so that you can be |
| 59 | notified with the {@link android.net.wifi.p2p.WifiP2pManager.ActionListener#onSuccess |
| 60 | ActionListener.onSuccess()} and {@link android.net.wifi.p2p.WifiP2pManager.ActionListener#onFailure |
| 61 | ActionListener.onFailure()} |
| 62 | methods. A {@link android.net.wifi.p2p.WifiP2pManager#WIFI_P2P_PEERS_CHANGED_ACTION} intent is |
| 63 | also broadcast if the {@link android.net.wifi.p2p.WifiP2pManager#discoverPeers discoverPeers()} |
| 64 | method discovers that the peers list has changed.</p> |
| 65 | |
| 66 | <h2 id="api">API Overview</h2> |
| 67 | |
| 68 | <p>The {@link android.net.wifi.p2p.WifiP2pManager} class provides methods to allow you to interact with |
| 69 | the Wi-Fi hardware on your device to do things like discover and connect to peers. The following actions |
| 70 | are available:</p> |
| 71 | |
| 72 | <p class="table-caption"><strong>Table 1.</strong>Wi-Fi Direct Methods</p> |
| 73 | |
| 74 | <table> |
| 75 | <tr> |
| 76 | <th>Method</th> |
| 77 | <th>Description</th> |
| 78 | </tr> |
| 79 | |
| 80 | <tr> |
| 81 | <td>{@link android.net.wifi.p2p.WifiP2pManager#initialize initialize()}</td> |
| 82 | <td>Registers the application with the Wi-Fi framework. This must be called before calling any other Wi-Fi Direct method.</td> |
| 83 | </tr> |
| 84 | |
| 85 | <tr> |
| 86 | <td>{@link android.net.wifi.p2p.WifiP2pManager#connect connect()}</td> |
| 87 | <td>Starts a peer-to-peer connection with a device with the specified configuration.</td> |
| 88 | </tr> |
| 89 | |
| 90 | <tr> |
| 91 | <td>{@link android.net.wifi.p2p.WifiP2pManager#cancelConnect cancelConnect()}</td> |
| 92 | <td>Cancels any ongoing peer-to-peer group negotiation.</td> |
| 93 | </tr> |
| 94 | |
| 95 | <tr> |
| 96 | <td>{@link android.net.wifi.p2p.WifiP2pManager#requestConnectionInfo requestConnectInfo()}</td> |
| 97 | <td>Requests a device's connection information.</td> |
| 98 | </tr> |
| 99 | |
| 100 | <tr> |
| 101 | <td>{@link android.net.wifi.p2p.WifiP2pManager#createGroup createGroup()}</td> |
| 102 | <td>Creates a peer-to-peer group with the current device as the group owner.</td> |
| 103 | </tr> |
| 104 | |
| 105 | <tr> |
| 106 | <td>{@link android.net.wifi.p2p.WifiP2pManager#removeGroup removeGroup()}</td> |
| 107 | <td>Removes the current peer-to-peer group.</td> |
| 108 | </tr> |
| 109 | |
| 110 | <tr> |
| 111 | <td>{@link android.net.wifi.p2p.WifiP2pManager#requestGroupInfo requestGroupInfo()}</td> |
| 112 | <td>Requests peer-to-peer group information.</td> |
| 113 | </tr> |
| 114 | |
| 115 | <tr> |
| 116 | <td>{@link android.net.wifi.p2p.WifiP2pManager.PeerListListener#discoverPeers discoverPeers()}</td> |
| 117 | <td>Initiates peer discovery </td> |
| 118 | </tr> |
| 119 | |
| 120 | <tr> |
| 121 | <td>{@link android.net.wifi.p2p.WifiP2pManager#requestPeers requestPeers()}</td> |
| 122 | <td>Requests the current list of discovered peers.</td> |
| 123 | </tr> |
| 124 | </table> |
| 125 | |
| 126 | |
| 127 | <p>{@link android.net.wifi.p2p.WifiP2pManager} methods let you pass in a listener, |
| 128 | so that the Wi-Fi Direct framework can notify your |
| 129 | activity of the status of a call. The available listener interfaces and the |
| 130 | corresponding {@link android.net.wifi.p2p.WifiP2pManager} method calls that use the listeners |
| 131 | are described in the following table:</p> |
| 132 | |
| 133 | <p class="table-caption"><strong>Table 2.</strong> Wi-Fi Direct Listeners</p> |
| 134 | |
| 135 | <table> |
| 136 | <tr> |
| 137 | <th>Listener interface</th> |
| 138 | <th>Associated actions</th> |
| 139 | </tr> |
| 140 | <tr> |
| 141 | <td>{@link android.net.wifi.p2p.WifiP2pManager.ActionListener}</td> |
| 142 | <td>{@link android.net.wifi.p2p.WifiP2pManager#connect connect()}, {@link |
| 143 | android.net.wifi.p2p.WifiP2pManager#cancelConnect cancelConnect()}, {@link |
| 144 | android.net.wifi.p2p.WifiP2pManager#createGroup createGroup()}, {@link |
| 145 | android.net.wifi.p2p.WifiP2pManager#removeGroup removeGroup()}, and {@link |
| 146 | android.net.wifi.p2p.WifiP2pManager.PeerListListener#discoverPeers discoverPeers()}</td> |
| 147 | </tr> |
| 148 | |
| 149 | <tr> |
| 150 | <td>{@link android.net.wifi.p2p.WifiP2pManager.ChannelListener}</td> |
| 151 | <td>{@link android.net.wifi.p2p.WifiP2pManager#initialize initialize()}</td> |
| 152 | </tr> |
| 153 | |
| 154 | <tr> |
| 155 | <td>{@link android.net.wifi.p2p.WifiP2pManager.ConnectionInfoListener}</td> |
| 156 | <td>{@link android.net.wifi.p2p.WifiP2pManager#requestConnectionInfo requestConnectInfo()}</td> |
| 157 | </tr> |
| 158 | |
| 159 | <tr> |
| 160 | <td>{@link android.net.wifi.p2p.WifiP2pManager.GroupInfoListener}</td> |
| 161 | <td>{@link android.net.wifi.p2p.WifiP2pManager#requestGroupInfo requestGroupInfo()}</td> |
| 162 | </tr> |
| 163 | |
| 164 | <tr> |
| 165 | <td>{@link android.net.wifi.p2p.WifiP2pManager.PeerListListener}</td> |
| 166 | <td>{@link android.net.wifi.p2p.WifiP2pManager#requestPeers requestPeers()}</td> |
| 167 | </tr> |
| 168 | </table> |
| 169 | |
| 170 | <p>The Wi-Fi Direct APIs define intents that are broadcast when certain Wi-Fi Direct events happen, |
| 171 | such as when a new peer is discovered or when a device's Wi-Fi state changes. You can register |
| 172 | to receive these intents in your application by <a href="#creating-br">creating a broadcast |
| 173 | receiver</a> that handles these intents:</p> |
| 174 | |
| 175 | <p class="table-caption"><strong>Table 3.</strong> Wi-Fi Direct Intents</p> |
| 176 | |
| 177 | <table> |
| 178 | <tr> |
| 179 | <th>Intent</th> |
| 180 | <th>Description</th> |
| 181 | </tr> |
| 182 | <tr> |
| 183 | <td>{@link android.net.wifi.p2p.WifiP2pManager#WIFI_P2P_CONNECTION_CHANGED_ACTION}</td> |
| 184 | <td>Broadcast when the state of the device's Wi-Fi connection changes.</td> |
| 185 | </tr> |
| 186 | <tr> |
| 187 | <td>{@link android.net.wifi.p2p.WifiP2pManager#WIFI_P2P_PEERS_CHANGED_ACTION}</td> |
| 188 | <td>Broadcast when you call {@link |
| 189 | android.net.wifi.p2p.WifiP2pManager.PeerListListener#discoverPeers discoverPeers()}. You |
| 190 | usually want to call {@link android.net.wifi.p2p.WifiP2pManager.PeerListListener#requestPeers |
| 191 | requestPeers()} to get an updated list of peers if you handle this intent in your |
| 192 | application.</td> |
| 193 | </tr> |
| 194 | <tr> |
| 195 | <td>{@link android.net.wifi.p2p.WifiP2pManager#WIFI_P2P_STATE_CHANGED_ACTION}</td> |
| 196 | <td>Broadcast when Wi-Fi Direct is enabled or disabled on the device.</td> |
| 197 | </tr> |
| 198 | <tr> |
| 199 | <td>{@link android.net.wifi.p2p.WifiP2pManager#WIFI_P2P_THIS_DEVICE_CHANGED_ACTION}</td> |
| 200 | <td>Broadcast when a device's details have changed, such as the device's name.</td> |
| 201 | </tr> |
| 202 | </table> |
| 203 | |
| 204 | |
| 205 | |
| 206 | <h2 id="creating-br">Creating a Broadcast Receiver for Wi-Fi Direct Intents</h2> |
| 207 | |
| 208 | <p>A broadcast receiver allows you to receive intents broadcast by the Android system, |
| 209 | so that your application can respond to events that you are interested in. The basic steps |
| 210 | for creating a broadcast receiver to handle Wi-Fi Direct intents are as follows:</p> |
| 211 | |
| 212 | <ol> |
| 213 | <li>Create a class that extends the {@link android.content.BroadcastReceiver} class. For the |
| 214 | class' constructor, you most likely want to have parameters for the {@link |
| 215 | android.net.wifi.p2p.WifiP2pManager}, {@link android.net.wifi.p2p.WifiP2pManager.Channel}, and |
| 216 | the activity that this broadcast receiver will be registered in. This allows the broadcast |
| 217 | receiver to send updates to the activity as well as have access to the Wi-Fi hardware and a |
| 218 | communication channel if needed.</li> |
| 219 | |
| 220 | <li>In the broadcast receiver, check for the intents that you are interested in |
| 221 | <code>{@link android.content.BroadcastReceiver#onReceive onReceive()}</code>. |
| 222 | Carry out any necessary actions depending on the intent that is |
| 223 | received. For example, if the broadcast receiver receives a {@link |
| 224 | android.net.wifi.p2p.WifiP2pManager#WIFI_P2P_PEERS_CHANGED_ACTION} intent, you can call the |
| 225 | {@link android.net.wifi.p2p.WifiP2pManager#requestPeers requestPeers()} method to get a list of |
| 226 | the currently discovered peers.</li> |
| 227 | </ol> |
| 228 | |
| 229 | <p>The following code shows you how to create a typical broadcast receiver. The broadcast |
| 230 | receiver takes a {@link android.net.wifi.p2p.WifiP2pManager} object and an activity as |
| 231 | arguments and uses these two classes to appropriately carry out the needed actions when the |
| 232 | broadcast receiver receives an intent:</p> |
| 233 | |
| 234 | <pre> |
| 235 | /** |
| 236 | * A BroadcastReceiver that notifies of important Wi-Fi p2p events. |
| 237 | */ |
| 238 | public class WiFiDirectBroadcastReceiver extends BroadcastReceiver { |
| 239 | |
| 240 | private WifiP2pManager manager; |
| 241 | private Channel channel; |
| 242 | private MyWiFiActivity activity; |
| 243 | |
| 244 | public WiFiDirectBroadcastReceiver(WifiP2pManager manager, Channel channel, |
| 245 | MyWifiActivity activity) { |
| 246 | super(); |
| 247 | this.manager = manager; |
| 248 | this.channel = channel; |
| 249 | this.activity = activity; |
| 250 | } |
| 251 | |
| 252 | @Override |
| 253 | public void onReceive(Context context, Intent intent) { |
| 254 | String action = intent.getAction(); |
| 255 | |
| 256 | if (WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION.equals(action)) { |
| 257 | // Check to see if Wi-Fi is enabled and notify appropriate activity |
| 258 | } else if (WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)) { |
| 259 | // Call WifiP2pManager.requestPeers() to get a list of current peers |
| 260 | } else if (WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) { |
| 261 | // Respond to new connection or disconnections |
| 262 | } else if (WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION.equals(action)) { |
| 263 | // Respond to this device's wifi state changing |
| 264 | } |
| 265 | } |
| 266 | } |
| 267 | </pre> |
| 268 | |
| 269 | <h2 id="creating-app">Creating a Wi-Fi Direct Application</h2> |
| 270 | |
| 271 | <p>Creating a Wi-Fi Direct application involves creating and registering a |
| 272 | broadcast receiver for your application, discovering peers, connecting to a peer, and |
| 273 | transferring data to a peer. The following sections describe how to do this.</p> |
| 274 | |
| 275 | <h3 id="setup">Initial setup</h3> |
| 276 | <p>Before using the Wi-Fi Direct APIs, you must ensure that your application can access |
| 277 | the hardware and that the device supports the Wi-Fi Direct protocol. If Wi-Fi Direct is supported, |
| 278 | you can obtain an instance of {@link android.net.wifi.p2p.WifiP2pManager}, create and register |
| 279 | your broadcast receiver, and begin using the Wi-Fi Direct APIs.</p> |
| 280 | <ol> |
| 281 | <li> |
| 282 | <p>Request permission to use the Wi-Fi hardware on the device and also declare |
| 283 | your application to have the correct minimum SDK version in the Android manifest:</p> |
| 284 | <pre> |
| 285 | <uses-sdk android:minSdkVersion="14" /> |
| 286 | <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" /> |
| 287 | <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" /> |
| 288 | <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" /> |
| 289 | <uses-permission android:name="android.permission.INTERNET" /> |
| 290 | <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> |
| 291 | </pre> |
| 292 | </li> |
| 293 | |
| 294 | <li>Check to see if Wi-Fi Direct is on and supported. A good place to check this is in your |
| 295 | broadcast receiver when it receives the {@link |
| 296 | android.net.wifi.p2p.WifiP2pManager#WIFI_P2P_STATE_CHANGED_ACTION} intent. Notify your |
| 297 | activity of the Wi-Fi Direct state and react accordingly: |
| 298 | <pre> |
| 299 | @Override |
| 300 | public void onReceive(Context context, Intent intent) { |
| 301 | ... |
| 302 | String action = intent.getAction(); |
| 303 | if (WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION.equals(action)) { |
| 304 | int state = intent.getIntExtra(WifiP2pManager.EXTRA_WIFI_STATE, -1); |
| 305 | if (state == WifiP2pManager.WIFI_P2P_STATE_ENABLED) { |
| 306 | // Wifi Direct is enabled |
| 307 | } else { |
| 308 | // Wi-Fi Direct is not enabled |
| 309 | } |
| 310 | } |
| 311 | ... |
| 312 | } |
| 313 | </pre> |
| 314 | </li> |
| 315 | |
| 316 | <li>In your activity's {@link android.app.Activity#onCreate onCreate()} method, obtain an instance of {@link |
| 317 | android.net.wifi.p2p.WifiP2pManager} and register your application with the Wi-Fi Direct |
| 318 | framework by calling {@link android.net.wifi.p2p.WifiP2pManager#initialize initialize()}. This |
| 319 | method returns a {@link android.net.wifi.p2p.WifiP2pManager.Channel}, which is used to connect |
| 320 | your application to the Wi-Fi Direct framework. You should also create an instance of your |
| 321 | broadcast receiver with the {@link |
| 322 | android.net.wifi.p2p.WifiP2pManager} and {@link android.net.wifi.p2p.WifiP2pManager.Channel} |
| 323 | objects along with a reference to your activity. This allows your broadcast receiver to notify |
| 324 | your activity of interesting events and update it accordingly. It also lets you manipulate the device's |
| 325 | Wi-Fi state if necessary: |
| 326 | <pre> |
| 327 | WifiP2pManager mManager; |
| 328 | Channel mChannel; |
| 329 | BroadcastReceiver mReceiver; |
| 330 | ... |
| 331 | @Override |
| 332 | protected void onCreate(Bundle savedInstanceState){ |
| 333 | ... |
| 334 | mManager = (WifiP2pManager) getSystemService(Context.WIFI_P2P_SERVICE); |
| 335 | mChannel = mManager.initialize(this, getMainLooper(), null); |
Scott Main | 8edad6f | 2012-03-09 10:55:50 -0800 | [diff] [blame] | 336 | mReceiver = new WiFiDirectBroadcastReceiver(manager, channel, this); |
Robert Ly | 12a1de0 | 2011-11-02 11:56:50 -0700 | [diff] [blame] | 337 | ... |
| 338 | } |
| 339 | </pre> |
| 340 | </li> |
| 341 | |
| 342 | <li>Create an intent filter and add the same intents that your |
| 343 | broadcast receiver checks for: |
| 344 | <pre> |
| 345 | IntentFilter mIntentFilter; |
| 346 | ... |
| 347 | @Override |
| 348 | protected void onCreate(Bundle savedInstanceState){ |
| 349 | ... |
| 350 | mIntentFilter = new IntentFilter(); |
| 351 | mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION); |
| 352 | mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION); |
| 353 | mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION); |
| 354 | mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION); |
| 355 | ... |
| 356 | } |
| 357 | </pre> |
| 358 | </li> |
| 359 | |
| 360 | <li>Register the broadcast receiver in the {@link android.app.Activity#onResume()} method |
| 361 | of your activity and unregister it in the {@link android.app.Activity#onPause()} method of your activity: |
| 362 | <pre> |
| 363 | /* register the broadcast receiver with the intent values to be matched */ |
| 364 | @Override |
| 365 | protected void onResume() { |
| 366 | super.onResume(); |
Scott Main | 8edad6f | 2012-03-09 10:55:50 -0800 | [diff] [blame] | 367 | registerReceiver(mReceiver, mIntentFilter); |
Robert Ly | 12a1de0 | 2011-11-02 11:56:50 -0700 | [diff] [blame] | 368 | } |
| 369 | /* unregister the broadcast receiver */ |
| 370 | @Override |
| 371 | protected void onPause() { |
| 372 | super.onPause(); |
Scott Main | 8edad6f | 2012-03-09 10:55:50 -0800 | [diff] [blame] | 373 | unregisterReceiver(mReceiver); |
Robert Ly | 12a1de0 | 2011-11-02 11:56:50 -0700 | [diff] [blame] | 374 | } |
| 375 | </pre> |
| 376 | |
| 377 | <p>When you have obtained a {@link android.net.wifi.p2p.WifiP2pManager.Channel} and |
| 378 | set up a broadcast receiver, your application can make Wi-Fi Direct method calls and receive |
| 379 | Wi-Fi Direct intents.</p> |
| 380 | </li> |
| 381 | |
| 382 | <p>You can now implement your application and use the Wi-Fi Direct features by calling the |
| 383 | methods in {@link android.net.wifi.p2p.WifiP2pManager}. The next sections describe how to do common actions |
| 384 | such as discovering and connecting to peers.</p> |
| 385 | </ol> |
| 386 | |
| 387 | <h3 id="discovering">Discovering peers</h3> |
| 388 | |
| 389 | <p>To discover peers that are available to connect to, call {@link |
| 390 | android.net.wifi.p2p.WifiP2pManager#discoverPeers discoverPeers()} to detect |
| 391 | available peers that are in range. The call to this function is asynchronous and a success or |
| 392 | failure is communicated to your application with {@link |
| 393 | android.net.wifi.p2p.WifiP2pManager.ActionListener#onSuccess onSuccess()} and {@link |
| 394 | android.net.wifi.p2p.WifiP2pManager.ActionListener#onFailure onFailure()} if you created a |
| 395 | {@link android.net.wifi.p2p.WifiP2pManager.ActionListener}. The |
| 396 | {@link android.net.wifi.p2p.WifiP2pManager.ActionListener#onSuccess onSuccess()} method only notifies you |
| 397 | that the discovery process succeeded and does not provide any information about the actual peers |
| 398 | that it discovered, if any:</p> |
| 399 | <pre> |
| 400 | manager.discoverPeers(channel, new WifiP2pManager.ActionListener() { |
| 401 | @Override |
| 402 | public void onSuccess() { |
| 403 | ... |
| 404 | } |
| 405 | |
| 406 | @Override |
| 407 | public void onFailure(int reasonCode) { |
| 408 | ... |
| 409 | } |
| 410 | }); |
| 411 | |
| 412 | </pre> |
| 413 | |
| 414 | <p>If the discovery process succeeds and detects peers, the system broadcasts the {@link |
| 415 | android.net.wifi.p2p.WifiP2pManager#WIFI_P2P_PEERS_CHANGED_ACTION} intent, which you can listen |
| 416 | for in a broadcast receiver to obtain a list of peers. When your application receives the {@link |
| 417 | android.net.wifi.p2p.WifiP2pManager#WIFI_P2P_PEERS_CHANGED_ACTION} intent, you can request a |
| 418 | list of the discovered peers with {@link |
| 419 | android.net.wifi.p2p.WifiP2pManager#requestPeers requestPeers()}. The following code shows how to set this up:</p> |
| 420 | <pre> |
| 421 | PeerListListener myPeerListListener; |
| 422 | ... |
| 423 | if (WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)) { |
| 424 | |
| 425 | // request available peers from the wifi p2p manager. This is an |
| 426 | // asynchronous call and the calling activity is notified with a |
| 427 | // callback on PeerListListener.onPeersAvailable() |
| 428 | if (manager != null) { |
| 429 | manager.requestPeers(channel, myPeerListListener); |
| 430 | } |
| 431 | } |
| 432 | </pre> |
| 433 | |
| 434 | <p>The {@link android.net.wifi.p2p.WifiP2pManager#requestPeers requestPeers()} method is also |
| 435 | asynchronous and can notify your activity when a list of peers is available with {@link |
| 436 | android.net.wifi.p2p.WifiP2pManager.PeerListListener#onPeersAvailable onPeersAvailable()}, which is defined in the |
| 437 | the {@link android.net.wifi.p2p.WifiP2pManager.PeerListListener} interface. The {@link |
| 438 | android.net.wifi.p2p.WifiP2pManager.PeerListListener#onPeersAvailable onPeersAvailable()} method |
| 439 | provides you with an {@link android.net.wifi.p2p.WifiP2pDeviceList}, which you can iterate |
| 440 | through to find the peer that you want to connect to.</p> |
| 441 | |
| 442 | <h3 id="connecting">Connecting to peers</h3> |
| 443 | |
| 444 | <p>When you have figured out the device that you want to connect to after obtaining a list of |
| 445 | possible peers, call the {@link android.net.wifi.p2p.WifiP2pManager#connect connect()} method to |
| 446 | connect to the device. This method call requires a {@link android.net.wifi.p2p.WifiP2pConfig} |
| 447 | object that contains the information of the device to connect to. |
| 448 | You can be notified of a connection success or failure through the {@link |
| 449 | android.net.wifi.p2p.WifiP2pManager.ActionListener}. The following code |
| 450 | shows you how to create a connection to a desired device:</p> |
| 451 | <pre> |
| 452 | //obtain a peer from the WifiP2pDeviceList |
| 453 | WifiP2pDevice device; |
| 454 | WifiP2pConfig config = new WifiP2pConfig(); |
| 455 | config.deviceAddress = device.deviceAddress; |
| 456 | manager.connect(channel, config, new ActionListener() { |
| 457 | |
| 458 | @Override |
| 459 | public void onSuccess() { |
| 460 | //success logic |
| 461 | } |
| 462 | |
| 463 | @Override |
| 464 | public void onFailure(int reason) { |
| 465 | //failure logic |
| 466 | } |
| 467 | }); |
| 468 | |
| 469 | </pre> |
| 470 | |
| 471 | |
| 472 | <h3 id="transferring">Transferring data</h3> |
| 473 | <p>Once a connection is established, you can transfer data between the devices with |
| 474 | sockets. The basic steps of transferring data are as follows:</p> |
| 475 | |
| 476 | <ol> |
| 477 | <li>Create a {@link java.net.ServerSocket}. This socket waits for a connection from a client on a specified |
| 478 | port and blocks until it happens, so do this in a background thread.</li> |
| 479 | |
| 480 | <li>Create a client {@link java.net.Socket}. The client uses the IP address and port of |
| 481 | the server socket to connect to the server device.</li> |
| 482 | |
| 483 | <li>Send data from the client to the server. When the client |
| 484 | socket successfully connects to the server socket, you can send data from the client to the server |
| 485 | with byte streams. </li> |
| 486 | |
| 487 | <li>The server socket waits for a client connection (with the {@link java.net.ServerSocket#accept()} method). This |
| 488 | call blocks until a client connects, so call this is another thread. When a connection happens, the server device can receive |
| 489 | the data from the client. Carry out any actions with this data, such as saving it to a file |
| 490 | or presenting it to the user.</li> |
| 491 | </ol> |
| 492 | |
| 493 | <p>The following example, modified from the <a href= |
| 494 | "{@docRoot}resources/samples/WifiDirectDemo/index.html">Wi-Fi Direct Demo</a> sample, shows you how |
| 495 | to create this client-server socket communication and transfer JPEG images from a client |
| 496 | to a server with a service. For a complete working example, compile and run the <a href= |
| 497 | "{@docRoot}resources/samples/WifiDirectDemo/index.html">Wi-Fi Direct Demo</a> sample.</p> |
| 498 | <pre> |
| 499 | public static class FileServerAsyncTask extends AsyncTask<Void, Void, String> { |
| 500 | |
| 501 | private Context context; |
| 502 | private TextView statusText; |
| 503 | |
| 504 | public FileServerAsyncTask(Context context, View statusText) { |
| 505 | this.context = context; |
| 506 | this.statusText = (TextView) statusText; |
| 507 | } |
| 508 | |
| 509 | @Override |
| 510 | protected String doInBackground(Void... params) { |
| 511 | try { |
| 512 | |
| 513 | /** |
| 514 | * Create a server socket and wait for client connections. This |
| 515 | * call blocks until a connection is accepted from a client |
| 516 | */ |
| 517 | ServerSocket serverSocket = new ServerSocket(8888); |
| 518 | Socket client = serverSocket.accept(); |
| 519 | |
| 520 | /** |
| 521 | * If this code is reached, a client has connected and transferred data |
| 522 | * Save the input stream from the client as a JPEG file |
| 523 | */ |
| 524 | final File f = new File(Environment.getExternalStorageDirectory() + "/" |
| 525 | + context.getPackageName() + "/wifip2pshared-" + System.currentTimeMillis() |
| 526 | + ".jpg"); |
| 527 | |
| 528 | File dirs = new File(f.getParent()); |
| 529 | if (!dirs.exists()) |
| 530 | dirs.mkdirs(); |
| 531 | f.createNewFile(); |
| 532 | InputStream inputstream = client.getInputStream(); |
| 533 | copyFile(inputstream, new FileOutputStream(f)); |
| 534 | serverSocket.close(); |
| 535 | return f.getAbsolutePath(); |
| 536 | } catch (IOException e) { |
| 537 | Log.e(WiFiDirectActivity.TAG, e.getMessage()); |
| 538 | return null; |
| 539 | } |
| 540 | } |
| 541 | |
| 542 | /** |
| 543 | * Start activity that can handle the JPEG image |
| 544 | */ |
| 545 | @Override |
| 546 | protected void onPostExecute(String result) { |
| 547 | if (result != null) { |
| 548 | statusText.setText("File copied - " + result); |
| 549 | Intent intent = new Intent(); |
| 550 | intent.setAction(android.content.Intent.ACTION_VIEW); |
| 551 | intent.setDataAndType(Uri.parse("file://" + result), "image/*"); |
| 552 | context.startActivity(intent); |
| 553 | } |
| 554 | } |
| 555 | } |
| 556 | </pre> |
| 557 | |
| 558 | <p>On the client, connect to the server socket with a client socket and transfer data. This example |
| 559 | transfers a JPEG file on the client device's file system.</p> |
| 560 | |
| 561 | <pre> |
| 562 | Context context = this.getApplicationContext(); |
| 563 | String host; |
| 564 | int port; |
| 565 | int len; |
| 566 | Socket socket = new Socket(); |
| 567 | byte buf[] = new byte[1024]; |
| 568 | ... |
| 569 | try { |
| 570 | /** |
| 571 | * Create a client socket with the host, |
| 572 | * port, and timeout information. |
| 573 | */ |
| 574 | socket.bind(null); |
| 575 | socket.connect((new InetSocketAddress(host, port)), 500); |
| 576 | |
| 577 | /** |
| 578 | * Create a byte stream from a JPEG file and pipe it to the output stream |
| 579 | * of the socket. This data will be retrieved by the server device. |
| 580 | */ |
| 581 | OutputStream outputStream = socket.getOutputStream(); |
| 582 | ContentResolver cr = context.getContentResolver(); |
| 583 | InputStream inputStream = null; |
| 584 | inputStream = cr.openInputStream(Uri.parse("path/to/picture.jpg")); |
| 585 | while ((len = inputStream.read(buf)) != -1) { |
| 586 | outputStream.write(buf, 0, len); |
| 587 | } |
| 588 | outputStream.close(); |
| 589 | inputStream.close(); |
| 590 | } catch (FileNotFoundException e) { |
| 591 | //catch logic |
| 592 | } catch (IOException e) { |
| 593 | //catch logic |
| 594 | } |
| 595 | |
| 596 | /** |
| 597 | * Clean up any open sockets when done |
| 598 | * transferring or if an exception occurred. |
| 599 | */ |
| 600 | finally { |
| 601 | if (socket != null) { |
| 602 | if (socket.isConnected()) { |
| 603 | try { |
| 604 | socket.close(); |
| 605 | } catch (IOException e) { |
| 606 | //catch logic |
| 607 | } |
| 608 | } |
| 609 | } |
| 610 | } |
| 611 | </pre> |